1. Study of the historical demography of the sheep population of the United States. These results will be used to help design a U.S. hydatid surveillance and control program. 2. Detailed epidemiological analysis of the hydatid disease control program on Cyprus. This is one of the few successful programs. It utilizes several new control features and the study results should be particularly valuable for future surveillance and control program design in the U.S. and other countries. 3. Begin construction of mathematical model of the epidemiology of hydatid disease.